Method of treating oils derived by thermal treatment of solid carbonaceous materials



United States Patent METHOD OF TREATING OILS DERIVED BY THER- MALTREATMENT OF SOLID CARBONACEOUS MATERIALS William J. Culbertson, .ln,and Thomas D. Nevens, Denver, and Werner D. Schnackenberg, Englewood,Col0., assignors to The Oil Shale Corporation, New York, N.Y., acorporation of Colorado No Drawing. Filed June 10, 1965, Ser. No.463,043

22 Claims. (Cl. 208-41) This application is a continuation-in-part ofour pending application Serial No. 106,493, filed May 1, 1961, nowabandoned.

This invention relates to the production of oil from solid carbonaceousmaterials and more particularly to a method for economically producingoil from solid carbonaceous materials characterized by a pour pointrequisite to pipeline transportation.

In crude form the heavy oils derived from naturally occurring deposits,such as petroleum, oil shale, tar sand, and the like, when cooled tendto thicken and progressively lose their ability to be moved in ordinaryfluid handling operations, such as pumping, pouring, and the like. Thetemperature at which such congelation is observed for a particular oilis commonly known as the pour point. There is little or no relationbetween the pour point and the viscosity of a given oil. At temperaturesslightly above the pour point of an oil, movement of the oil byordinary, fluid handling operations often is extremely difiicult andcommercially impractical. At temperatures approximating or below thepour point of a oil, ordinary fluid handling of the oil is even morediificult. Therefore, hydrocarbon oils characterized by a pour pointcomparable to or higher than temperatures reasonably expected in thenormal handling and movement of the oil generally are unsuitable unlessexpensive pour-point depressants and/or expensive processing arepreliminarily employed. The relationship between pour point and expectedtemperatures in handling and movement is especially important when it isdesired to transport heavy oil by pipeline over relatively longdistances.

Crude oil produced by conventional recovery operations from petroleumnormally is characterized by a pour point which enables such oil to besuitably transported by pipeline without special treatment at groundtemperature conditions above about 40 P. On the other hand, oilsproduced by thermal treatment of solid carbonaceous materials andparticularly shale oils usually are characterized by a pour point on theorder of about 80 F. to about 100 F. Accordingly, if conventional meansare employed to lower the pour point of such oils to an acceptablelevel, even greater expense is involved. Moreover, problems occasionedby the high pour point of oils obtained by thermally treating solidcarbonaceous material are aggravated by the fact that the greatpreponderance of raw materials, such as oil shale, usually are removedfrom population centers and low-cost transportation facilities, such asnavigable water. Consequently, the only commercially practical means forconveying the crude oil produced at the deposit sites to market is bypipeline transportation.

As a result of the relatively high pour point of crude shale oil or oilderived from oil-bearing sands and the like, the refining industry hasbeen unable competitively to employ such oil despite the fact that atthe deposit site the crude oils can be produced at considerably lesscost than petroleum crudes.

By virtue of the significant difference in the composition of crude oiland oils derived by thermal treatment of such carbonaceous materials asoil shale and oil or tar sand, processes which are suitable for loweringthe pour point of petroleum crudes are not commercially desirable. Inone method which has been suggested for reducing the pour point of crudeshale oil, the oil is subjected to cracking at temperatures generally inexcess of about 900 F. and under elevated pressures. Under theconditions requisite in such pour point lowering treatments, theformation of heavy fuel oil constituents is undesirably accompanied bythe formation of substantial amounts of light gases and coke which areeconomically prohibitive in terms of end product losses. Coking is perse undesirable due to its fouling of equipment and reduction effected inheat transfer. In addition, the conditions utilized in the suggestedcoking processes are not selective in their cracking of the heavierhydrocarbons, with the result that the treated shale oil is undesirablyaltered in composition by additional cracking of a substantial amount ofthe lighter hydrocarbons its contains.

Another method which has been suggested for reducing the pour point ofcrude oils produced by thermal treatment of carbonaceous materialsinvolves the incorporation of pour point depressants as in the case ofpetroleum crudes. As previously indicated, a significant reduction inpour point can be realized only by incorporation of large amounts of theexpensive depressants. Aside from the economics involved, it isundesirable to introduce such large amounts of a foreign material into acrude oil which subsequently must be extensively refined.

Therefore, the prior art has not provided an eflicient, inexpensivemethod for significantly lowering the pour point of shale oil and otherhigh pour point oils produced by thermally treating solid carbonaceousmaterial and thus making such oils available to the industry bypipeline.

Accordingly, it is the primary object of the present invention toproduce from a crude oil derived by thermally treating solidcarbonaceous material an oil which is characterized by a low pour point.

A particular object of the invention is the production of a low pourpoint oil from an oil derived from thermal treatment of solidcarbonaceous material by means which do not require appreciable crackingof the crude oil or addition of a foreign pour point depressant.

It is another object of the present invention to provide an inexpensivemethod for significantly lowering the pour point of shale oil ascompared to processes previously suggested.

It is a further object of the present invention to provide a method forlowering the pour point of shale oil by a thermal treatment wherein thevalues in the light ends are preserved.

It is still another object of the present invention to provide a methodfor effecting a reduction in the pour point of shale oil by a thermaltreatment wherein substantially no coking is obtained. I

It is a particular object of the present invention to provide a methodfor lowering the pour point of shale oil to render the shale oilsuitable for handling and pipeline transportation.

It is an additional object of the present invention to provide a shaleoil suitable for pipeline transmission and economically competitive withcrude oil.

Broadly described, the present invention is a method for treating aheavy fraction separated under substantially non-cracking conditionsfrom a crude oil derived by thermal treatment of solid carbonaceousmaterial, to produce said heavy fraction and at least one lightfraction, which method comprises heat treating said separated heavyfraction alone at a temperature above about 600 F. and below the pointof incipient thermal decomposition of the heavy fraction for a period oftime which is inversely proportional to said temperature to produce aproduct which, when combined with at least part of a light fraction,results in an oil having a pour point lower than that of the originalcrude oil; said heat treatment producing substantially nonon-condensible hydrocarbons and substantially no elemental carbon.

A preferred embodiment of the present invention is a method for reducingthe pour point of an oil derived by thermal treatment of solidcarbonaceous material which comprises treating said oil undersubstantially noncracking conditions to obtain at least one lightfraction and an oil residue, heat treating said oil residue at atemperature above about 600 F. and below the point of incipient thermaldecomposition of the residue for a period of time which is inverselyproportional to said temperature to produce a product which, whencombined with a light fraction results in an oil having a pour pointlower than that of the original crude oil, said heat treating processproducing substanially no non-condensible hydrocarbons and substantiallyno elemental carbon; and combining said modified oil residue productwith at least a portion of a light fraction to provide an oil readilytransportable by pipeline.

Also included in the invention is an oil product pre pared by heattreating a separated heavy residue formed by separating said residue anda light fraction under substantially non-cracking conditions from acrude oil derived and produced by thermal treatment of solidcarbonaceous material; said heat treatment of the residue beingconducted at a temperature between about 600 F. and the point ofincipient thermal decomposition of the residue and for a period of timewhich is inversely proportional to said temperature to produce a productwhich, upon combination with at least part of the light fraction,results in an oil having a pour point lower than that of the originalcrude oil.

Preferably, the heat treatment of the heavy fraction in accordance withthe invention is continued for a period sufficient to produce a treatedheavy fraction which, on combination with part of the light fraction,will produce an oil having a pour point at least about F. below that ofthe original crude oil.

While the precise effect of the heat treatment of the heavy highmolecular weight fraction containing the Waxes, asphaltenes, and thelike is not completely clear, it is theorized that some portion of theheavy fraction undergoes a molecular modification and/or rearrangementwhich results in a marked improvement in pour point and reduction inthixotropy after combination with lighter hydrocarbon oil fractions. Themolecular Weight of the heavier hydrocarbons is not appreciably affectedby any such alteration in molecular structure. Moreover, the pour pointof the heavy fraction which has been treated in accordance with theinvention is not appreciably changed from that of the heavy fractionprior to treatment.

The temperature and conditions utilized in the invention avoidappreciable formation of light gases or of coke. These substancesrepresent undesirable loss in yield in processing oils, and in themethod of the invention are not formed even as by-products.

The carbonaceous materials from which the feed stocks employed in theprocess of the invention are derived include, without limitation, oilshale, bituminous sands, brown coal, peat and the like. The oilcontemplated for treatment by the method of the present invention is anycrude oil or heavy oil fraction derived from these sources as opposed topetroleum hydrocarbons. Crude oils produced from oil shale deposits inthe United States usually contain up to about 50 percent by weight ofhydrocarbons boiling above heavy fuel oil and are characterized by apour point above about 70 F., usually from about 80 F. to about 100 F.These shale oils are especially suited for treatment in accordance withthe present invention.

Oils formed by combination of the treated heavy fraction with lighterhydrocarbons are characterized by pour point and thixotropic propertiesmuch improved over that of the crude oil employed as the startingmaterial. In accordance with the present invention, crude oilsunsuitable for handling and transmission by pipeline by virtue of theirpour point characteristics readily may be adapted for such purposes.Shale oil having a pour point of above about 80 F. to about 100 F.suitably may be treated by the process of the invention to reduce thepour point to a value in the range of from about 10 F. to 40 F. orlower. Shale oils treated in accordance with the invention also aresignificantly less thixotropic than untreated shale oils of comparablepour point and are more nearly Newtonian. In general the rheology ofoils produced by thermal treatment of solid carbonaceous materials maybe significantly improved by employing the process of the invention.

In the method of the invention the heavy fraction of a suitable oil isheat treated in a vessel to a temperature of at least about 600F. butbelow the temperature of incipient thermal decomposition of the oil. Inthis range of temperatures, usually between about 600F. and about 800F.,the desired modification is effected without formation of appreciableamounts of non-condensible gases and coke. The range of temperatureswhich may be employed to accomplish the requisite molecular modificationof a particular heavy fraction will depend upon the composition of theparticular oil and may be predetermined by appropriate runs on the oil.For oils derived from oil shale, the desired molecular modificationpreferably is carried out at temperature in the range from about 600F.to about 800F., and preferably from about 700F. to about 750F.

The pressure in the vessel in which the oil is heattreated suitably maybe any pressure which does not effect the formation of coke andnon-condensible gases. Pressures preferred are in the range of fromabout 1 to about 2 atmospheres, and more preferably, the pressureemployed is the autogenesis pressure. Moderate pressure may bebeneficial in reducing foaming and vaporization during the digestingstep.

The oil undergoing treatment preferably is digested in a suitable vesselat the autogenesis pressure for the time requisite to effect the desiredmolecular modification. Normally, where a pour point diminution of atleast about 10F is desired in a composite oil containing the heatedresidue and lighter hydrocarbons, a digestion period of at least about30 minutes is employed. The actual time period required in the digestionstep naturally depends upon the particular oil being treated, thespecific temperature and pressure conditions employed in the digestion,and the particular pour point properties desired in the final oil. Thedigestion desirably is terminated when the treated fraction will producethe desired diminution in pour point and the required rheologicalcharacteristics.

In the case of oil derived from American oil shale, the preferreddigestion time period is in the range of from about 20 minutes to about3 hours. Substantial reduction in pour point can be obtained with someoils with a digestion period as low as 10 minutes, and even as low as 1minute, particularly at the higher soaking temperatures. Digestion timesof longer than 3 hours may be employed but generally are unnecessary andnormally produce no further significant improvement in rheologicalproperties or pour point reduction.

The invention in a preferred embodiment contemplates treatment of oilsfrom solid carbonaceous material, for example crude Colorado shale oil,wherein the lower boiling hydrocarbons are removed prior to thedigestion step. The lower boiling hydrocarbons may be removed by anysuitable method, preferably by a fractionation of the oil undernon-cracking conditions to obtain a light fraction comprising such lighthydrocarbons and an oil residue. Fractional condensation, solventextraction procedures and the like, also may be employed to separate theresidual heavy fraction from the crude. In the preferred practice of theinvention it is desirable to remove as large a proportion ofhydrocarbons boiling above waxes, tars, and asphalts as possible withoutnecessitating the use of cracking conditions.

When the crude oil is derived by pyrolysis of oil shale, thefractionation, solvent extraction or other procedure employed to obtaina heavy, high molecular weight fraction preferably is controlled toproduce such a fraction consisting of from about 5 to about 70 percentby volume of the original crude oil charge. Preferably, the crude oil isfractionated to provide a residue consisting of from about to about 30percent by volume of the original crude. Desirably, such residue issoaked for a period of from about thirty minutes to about one hour at atemperature of about 700F. to about 750F.

The light fraction removed from the oil is collected and in thepreferred embodiment of the invention subsequently is combined in wholeor in part with the treated residue to form a shale oil of low pourpoint.

It is contemplated that light fractions obtained from shale oils otherthan that from which the oil residue is obtained and treated also may becombined with such treated residue and may in whole or in part replacethe light ends preliminarily separated. When a light hydrocarbonfraction is combined with the modified oil residue, it is preferred thatthe modified oil residue be at moderate temperatures before the additionof the light fraction thereto to prevent vaporization of low molecularweight components of the admixture. This cooling may be accomplished inany expedient manner.

If the shale oil treatment is carried out in a continuous manner as ispreferred, it is also preferred that the residue be removed from thefractionating or extracting vessel prior to being heated at temperatureshigher than those employed in the distillation or extraction process.This will prevent the retention of heavy constituents for long periodsof time at elevated temperatures with possible resultant carbonizationor production of non-condensibles. Alternatively, in such a continuousprocess the heat treatment may be carried out in situ without theaddition of external heat, such as by soaking in a separating vessel.

When the shale oil treatment is conducted as a batchtype operation, theretention or soaking vessel and the fractionating vessel, with propercontrol of conditions, may be the same without encountering carbonizingconditions and production of non-condensibles.

The heat treatment step of the present invention appropriately may becarried out in equipment which is made an integral part of the plantequipment employed in the thermal treatment of the solid carbonaceousmaterial. In this manner crude oil advantageously may be treated at theproduction site and suitably prepared for movement to a distant refineryby pipeline transportation.

In accordance with a further embodiment of the invention, the heattreated heavy fraction is added to petroleum oils or petroleum oilfractions to, inter alia, reduce the pour point of such oils and oilfractions. The amount of heat treated heavy fraction added depends onthe degree of pour point reduction required. Amount of heat treatedheavy fraction up: to about thirty percent by weight preferably areadded to the petroleum oil or oil fraction.

While the oil to be treated in accordance with the process of thisinvention may be produced from soild carbonaceous material, such as oilshale, tar sands, and the like, by any of the known processes, itpreferably is produced by the process of Aspegren US. patent No.3,025,223. Pursuant to the Aspergren process, particulate oil shale oroil-bearing said or similar material is pyrolyze-d in a revolving drum.The heat for the pyrolysis is furnished in the revolving drum bysolid-to-solid milling contact with heat-carrying bodies such as ballsof refractory material less attritionable than the oilor kerogen-bearingfeed. The heat-carrying bodies are separated from the pyrolysis residueand then preferably are reheated by combustion of the carbonaceouspyrolysis residue in a separate zone. The reheated bodies then arerecirculated to the pyrolysis drum in solid-to-solid milling contactwith fresh feed. Such process has been found more effective than anyother known pyrolysis process for production of oil from solidcarbonaceous material and particularly from oil shale.

The process of this invention is to be distinguished from thevisbreaking techniques practiced by the prior art. The differencebetween visbreakin g, where considerable cracking is desired and in factis obtained along with substantial amounts of coke, is illustrated bythe fact that the distillation curves of visb-roken oils are materiallydifferent from those of the original stock. The distillation curves ofoils treated in accordance with the present invention, on the otherhand, are not appreciably different from those of the original stock.Further, in visbreaking techniques the oil or oil fraction treated isnot combined with lighter fractions to produce a composite oil.Moreover, visbroken oils in contradistinction to the treated heavyfractions of the invention, are characterized by pour points lower thanthe original oil or oil fraction. In all case where pour points havebeen taken on the heavy fraction before and after heat treatment inaccordance with the invention, such values have been within the 5 F.margin of error provided for in standard pour point determinationtechniques.

Having generally described the invention, the following examples are.given specifically to illustrate embodiments of the method of theinvention. The examples are given for illustrative purposes only and arenot intended to limit the scope of the invention. The pour pointsreferred to in the general description and in the examples weredetermined by ASTM Designation D97-47. Pour points were taken to thenearest 5 F. The distillations employed in the examples were conductedaccording to ASTM Designation D-l160-52T.

Example I tures of about 650 F., 700 F., and 750 F., fora time period ofabout 1 hour. No discernible amount of noncondensibles or elementalcarbon were produced. At the end of the heating period each treatedresidue was cooled to about 70 F., tested for pour point properties,

and recombined with its corresponding, previously removed lightfraction. Each oil resulting from the recombination was then tested forits pour point characteristics. The results of the various runs are setforth in the table below:

The general procedure of Example I was repeated in a series of runswherein various residues were heat treated for a period of 1 hourfollowing removal of the light fractions indicate-d in the table below.Runs 1, 2 and 3 Of Example I are included for comparative purposes.There 7 was no discernible production of either non-condensiblehydrocarbons or elemental carbon. The results are set with varyingamounts'of the various lighter fractions and pour point determinationsmade.

Light Fraction Removed, Percent by Volume 70 50 3O 90 80 70 65 Theresults are set Residue Pour Point Before Soaking 80 95 90 80 90 95 9590 80 Residue Pour PointAfter Soaking-. so 90 90 95 so 85 95 85 so FinalOil Pour Point, F 50 7o 75 55 45 2o 15 50 5 TABLE Volume Volume PourPoint Example I Run N0. Percent of Percent of of Combined Residue 040%Mixture, F. The general procedure of Example I was repeated in Fractiona series of runs employing the same shale oil wherein temperature andtreating time were varied as indicated in 2 gg :5? the table below. Alight fraction of 70% by volume 4o 50 6 was removed and the residuetreated as indicated in the $3 g3 8 table below. Runs 1, 2 and 3 arerecorded for purposes Volume perof comparison. There was no discernibleproduction of oentot2070% non-condensibles or elemental carbon. Theresults of Fracnm these nuns are tabulated below. 0 100 0 75 80 40 oo 8055 45 8O 70 3o 85 35 Volume Percent of 0-36% Fraction TABLE 0 100 0 1585 25 75 Time, hr .25 1.0 2.0 50 55 -15 70 30 10 Run 12 13 14 1 2 3 1516 Volume Percent of 35-70% Temp.,F 650 700 750 550 700 750 550 700Fraction Residue Pour Poin F.Belore Soaking. so so so so so so 0 100 90Residue Pour Point, 25 75 90 F.After Soaking" so 75 so so so 40 oo 35Final Oil Pour 55 45 90 Point,F 70 4o 15 3o 15 5 70 30 85 Volume Percentof 0-507}, Fraction o 100 40 1o 90 15 20 so 5 3o 70 -10 a 0 5 Example IV6O 40 20 70 30 40 The general procedure of Example I was repeated ex-Volume Per cept for removing a light fraction of 36 volume percent centot50-70% and employing a soaking time of 2 hours at 600 F. Fraction Thepour point of the final recombined oil was 55 F. g 82 No discerniblenon-condensibles or elemental. carbon 28 0 95 were produced. 60 23 32Example V 70 30 95 Volume Per- A Colorado shale 011 having a pour pointof about i. g 80 F. was fractionated to produce a heavy residue con- 0stituting a -100% fraction, i.e., 30% by volume, and 20 228 variouslighter fractions as set out in the table below. g3 g3 23 The residuewas heat treated in accordance with the ini 65 15 vention at atemperature of about 700 F. for a period 4% 22 i3 of about 1 hour. Thepour point of the residue before and after heat treatment was F. Therewas no dis- 35 30 cermble production of either non-condensible hydrocar-103 2g 28 bons or free carbon. The treated residue was combined 9 Fromthe data given above it is apparent that by combining the treatedresidue with various amounts of the lighter fractions, especially thelighter ends of the originally separated light fraction, oils ofextremely low pour point may be produced.

Example VI A Colorado oil shale was pyrolyzed to produce a vaporizedeffluent which, when condensed, produced a shale oil characterized by apour point of 80 F. The vaporous efiluent was fractiona'lly condensed toproduce the fractions indicated in the table below in terms of weightpercent of the efiluent. These fractions were soaked for the lengths oftime shown at a temperature of about 730 F. The soaked fractions werecombined with the light ends in each case to give the following finalpour points:

Run N 0. Percent Soaking Time, Pour Point,

Soaked Hrs. F.

Example VII Example VIII A crude Colorado shale oil having a pour pointof 70 F. was fractionated to provide .a light fraction consisting ofabout 72% by volume of the crude oil and a heavy residue of about 28% byvolume. Portions of the residue were heated at the temperatures and forthe time periods set forth below. No discernible amount ofnoncondensibles or elemental carbon were produced. At the end of theheating period each treated residue was cooled to about 70 F. andrecombined with its corresponding, previously removed light fraction.Each oil resulting from the recombination or blending was then testedfor its pour point characteristics. The results of the various runs areset forth in the table below.

TAB LE Pour Point of Blended Oil Soaking Temperature F.)

Run No. Soaking Time (Minutes) z we-sr s wws s sws l-WUI HtOCAJODPOOQDQsloooowmwmuqoocqcn We claimf 4 1. A method for treating a heavy fractionseparated .under substantially non-cracking conditions from a crude oilderived by thermal treatment of solid carbonaceous material, to producesaid heavy fraction and at least one light fraction which methodcomprises heat treating said separated heavy fraction alone at atemperature above about 600 F. and below the point of incipient thermaldecomposition of the heavy fraction for a period of time which isinversely proportional to said temperature to produce a product whichwhen combined with at least part of a light fraction, results in an oilhaving a pour point lower than that of the original crude oil, said heattreatment producing substantially no non-condensible hydrocarbons =andsubstantially no elemental carbon.

2. The method according to claim 1 wherein the solid carbonaceousmaterial is oil shale.

3. The method according to claim 1 wherein the crude oil is a shale oilhaving a pour point of at least about 4. The method according to claim 1wherein the heavy fraction is heat treated at a temperature of fromabout 600 F. to :about 800 F.

5. The method according to claim 1 wherein the heavy fraction is heattreated for a period between about 1 minute to about 3 hours.

6. The method according to claim 1 wherein the heat treatment of theheavy fraction is conducted at the autogenesis pressure.

7. A method for reducing the pour point of an oil derived by thermaltreatment of solid carbonaceous ma terials and containing hydrocarbonswhich comprises treating said oil under substantially non-crackingconditions to obtain at least one light fraction and an oil residue,heat treating said oil residue at a temperature above about 600 F. andbelow the point of incipient thermal decomposition of the residue for aperiod of time which is inversely proportional to said temperature toproduce a product which when combined with a light fraction results inan oil having a pour point lower than the original crude oil, said heattreatment producing substantially no non-condensibie hydrocarbons andsubstantially no elemental carbon; and combining said modified oilresidue product with at least a portion of a light fraction to producean oil of lower pour point than the original crude.

8. The method according to claim 7 wherein the solid carbonaceousmaterial is an oil shale.

9. The method according to claim 7 wherein the oil derived from thermaltreatment of solid carbonaceous material is a shale oil having a pourpoint between about 70 F. and about F.

10. The method according to claim 7 wherein the residue heat threated isunder a pressure not in excess of 2 atmospheres.

11. The method according to claim 7 wherein said residue represents fromabout 5% to about 70% by volume of said crude sh-ale oil.

12. The method according to claim 7 wherein the residue is heat treatedfor between about 1 minute and about 3 hours at a temperature betweenabout 600 F. and about 800 F.

13. A method for reducing the pour point of crude shale oil whichcomprises treating a crude shale oil at non-cracking conditions toproduce a light fraction and an oil residue containing waxes and.asphaltenes, heat treating said oil residue at a temperature of fromabout 600 F. to about 800 F., said heat treatment producingsubstantially no non-c-ondensible hydrocarbons and substantially no freecarbon and being continued for a period of time which is inverselyproportional to said temperature to producing of a treated residue whichwhen combined with at least a portion of a light fraction, produces anoil characterized by a pour point at least 10 F. lower than that of thecrude shale oil.

14. The method according to claim 13 wherein said crude shale oil has apour point in the range of from about 70 F. to about 100 F.

15. The method according to claim 13 wherein said residue representsfrom about to about 70% by volume of said crude shale oil.

16. The method according to claim 13 wherein the residue is heat treatedin the range of from about 650 F. to about 750 F.

17. The method according to claim 13 wherein said time period is in therange of from about 1 minute to about 3 hours.

, 18. The method according to claim 13 wherein all of said lightfraction is combined with said modified oil residue.

19. An oil product prepared by heat treating a separated heavy residueformed by separating said residue and a light fraction undersubstantially non-cracking conditions from a crude oil derived bythermal treatment of solid carbonaceous material; said heat treatment ofthe residue being conducted at a temperature between about 600 F. andthe point of incipient thermal decomposition of the residue and for aperiod of time which is inversely proportional to said temperature toproduce a product which, upon combination with at least part of a lightfraction, results in an oil having a pour point lower than that of theoniginal crude oil.

20. An oil product according to claim 19 in which the oil produced bythermal treatment of solid carbonaceous material is shale oil.

21. A method for reducing the pour point of crude shale oil whichcompnises treating a crude shale oil at non-cracking conditions toproduce from 30 to 95 volume percent of said crude shale oil of a lightfraction and from 70 to 5 volume percent of said crude shale oil of anoil residue; ceasing the production of light fraction;

heating said residue at a temperature between about 600 F. and the pointof incipient thermal decomposition of the residue for a period of atleast about 10 minutes Without further removal of substantial quantitiesof light fraction and with substantially no formation of non-condensiblehydrocarbons and free carbon; and recombining said light fraction andheat-treated residue to provide a product having a substantially lowerpour point than the original crude shale oil.

22. A pour point depressant prepared by heat treating a separated heavyresidue formed by separating said residue and a light fraction undersubstantially non-cracking conditions from shale oil derived by thermaltreatment of oil shale; said heat treatment being conducted at atemperature between about 600 F. and the point of incipient thermaldecomposition of the residue and for a period of at least about 1minute, said period varying inversely with said temperature.

References Cited by the Examiner UNITED STATES PATENTS 781,240 1/1905Stark 208-106 1,886,262 11/1932 Nielson 208l1 1,953,039 3/1934 Bonnell208-19 2,315,935 4/1943 Child 20815 2,885,338 5/1959 Evans 20811 OTHERREFERENCES Bell, H. S.: Oil Shale and Shale Oils, D. Van Nostrand Co.Inc., New York, 1948 (Ohapt. VIII).

Sach anen: The Chemical Constituents of Petroleum, Reinhold Publ. Corp.,New York, 1945 (pp. 304305).

DANIELE. WYMAN, Primary Examiner.

P. KONOPKA, Assistant Examiner.

7. A METHOD FOR REDUCING THE POUR POINT OF AN OIL DERIVED BY THERMALTREATMENT OF SOLID CARBONACEOUS MATERIALS AND CONTAINING HYDROCARBONSWHICH COMPRISES TREATING SAID OIL UNDER SUBSTANTIALLY NON-CRACKINGCONDITIONS TO OBTAIN AT LEAST ONE LIGHT FRACTION AND AN OIL RESIDUE,HEAT TREATING SAID OIL RESIDUE AT A TEMPERATURE ABOVE ABOUT 600*F. ANDBELOW THE POINT OF INCIPIENT THERMAL DECOMPOSITION OF THE RESIDUE FOR APERIOD OF TIME WHICH IS INVERSELY PROPORTIONAL TO SAID TEMPERATURE TOPRODUCE A PRODUCT WHICH WHEN COMBINED WITH A LIGHT FRACRTION RESULTS INAN OIL HAVING A POUR POINT LOWER THAN THE ORIGINAL CRUDE OIL, SAID HEATTREATMENT PRODUCING SUBSTANTIALLY NO NON-CONDENSIBLE HYDROCARBONS ANDSUBSTANTIALLY NO ELEMENTAL CARBON; AND COMBINING SAID MODIFIED OILRESIDUA PRODUCT WITH AT LEAST A PORTION OF A LIGHT FRACTION TO PRODUCEAN OIL OF LOWER POUR POINT THAN THE ORIGINAL CRUDE.